The present invention relates to a CT gantry, and more specifically to a self adjusting bearing used on a CT gantry.
Current CT gantries have a main bearing, a big pulley and a rotating base for support and rotation of all rotating parts in the CT gantry. The main bearing is one of the most critical mechanical parts for the CT gantry.
However, the main bearing of a current CT gantry has many drawbacks. First, the current CT main bearing is expensive, which increases the total cost of the ICV in the CT system. Second, the CT main bearing is a slewing bearing with a very complicated structure. Most of the bearings are purchased from abroad, which have a long lead time, and are difficult for localization. Third, the main bearing and the rotating base are in a cantilever beam structure, which creates a significant overturn moment of the main bearing. This results in a high failure rate and low resistance for vibration and shock during shipment and handling of the main bearing. Finally, the failure of the main bearing, such as noise and screw skip issues, in the field leads to the replacement of the whole gantry or even CT system, which will necessarily increase service expenses and customer complaints.
U.S. Pat. No. 5,473,657 discloses a bearing assembly for supporting the rotating base. The bearing assembly is composed of a plurality of supporting rollers, which are in contact with an outer periphery of the rotating base. The supporting rollers may be made of a resilient material to dampen vibration transfer from the frame to the rotating base. These supporting rollers have a cylindrical shape and thus can limit the movement of the rotating base in the scanning plane defined by X-Y. However, these supporting rollers having a cylindrical shape cannot limit the rotating base's movement in the Z-direction perpendicular to the scanning plane. Therefore, three additional resilient roller pairs are used for contacting the side edge of the rotating base so as to limit the rotating base's movement in the lateral direction, namely, the Z direction.
When the rotating base expands or contracts in the scanning plane as a result of temperature changes, a sliding friction will occur between the three pairs of resilient rollers contacting the side edge and the rotating base. This will increase material wear of the resilient rollers and the rotating base.